Radiation induced segregation in titanium diboride

Radiation-induced segregation (RIS) is one of the most dramatic changes that can occur at grain boundaries (GBs) during irradiation. In ceramics, RIS has been rarely studied and the underlying mechanisms are not well understood. Here, we used a combination of experiments and simulations to demonstrate RIS in TiB2. Specifically, we found that radiation causes a significant B depletion and a modest Ti enrichment in the GB regions. We demonstrate that B depletion is a result of the formation of BI-VTi complex and the migration of B vacancies to the GB, where the BI represents B interstitial and VTi represents the Ti vacancy. The Ti enrichment is driven by the differences between the diffusivities of Ti interstitials and vacancies. The distinct RIS mechanisms found in TiB2 shed new light on the relation between the complex energy landscape and defect evolution in ceramics. [Display omitted]